Due to the compactness, high speed, and moduleless, and small sizes of modern electronic devices, heat dissipation of the electronic devices must be promoted with the improvement of the technologies.
Currently, wind blowing from heat dissipating fans has a wide coverage and is weak. Moreover, dead ends are formed. With reference to FIG. 2, a direct blowing fan D blows wind by using blades A. Thereby, the wind in the center of the fan is weak or no wind blows out in the center of the fan so as to form a dead point E.
For the seat B of the heat dissipating device, it is often that the center of the heat dissipating seat has highest thermal energy so that the heat dissipation is not preferred. Theoretically, the larger the heat dissipating area, the higher the heat dissipating efficiency. Thereby, more and more heat dissipating fins or pin fins cause stronger heat dissipating effect. However, in prior art heat dissipating seat, since tops C of the fins or pin fins have interface impedance which increase with the increment of the density of the fins or pin fins. Thereby, the density of the fins or pin fins are confined, otherwise the wind will reflect from the tops of the fins or pin fins so that the wind can not flow into the heat dissipating device, as a result the heat dissipating efficiency is decreased greatly.
In another prior art, turbine form heat dissipating fan, as fan D1 illustrated in FIG. 2-1, is used. Since the intensity of wind is strong and the wind direction H1 cannot be controlled. Thereby, the wind flow H1 is unsteady. Turbulent flow or high density flow is easily generated so as to form another kind of heat dissipating dead point E2. Thereby, the improvement of heat dissipating efficiency is limited.
Another improvement is water-cooled heat dissipating devices, however, such kind devices easily generate wet moistures. This is unbeneficial to electronic products.